The fabrication of modern circuits typically involves several steps. Integrated circuits are first fabricated on a semiconductor wafer, which contains multiple duplicated semiconductor chips, each comprising integrated circuits. The semiconductor chips are then sawed from the wafer and packaged. The packaging processes have two main purposes: to protect delicate semiconductor chips and connect interior integrated circuits to exterior pins.
With the increasing demand for more functions, Package-on-Package (PoP) technology, in which two or more packages are bonded for expanding the integration ability of the packages, is developed. With a high degree of integration, the electrical performance of the resulting PoP package is improved due to the shortened connecting paths between components. By using PoP technology, package design becomes more flexible and less complex. Time-to-market is also reduced.